Open-angle glaucoma is a major cause of visual impairment in Black populations. Clinical experience suggests an unusually high glaucoma risk in Barbados, W.I., where most citizens are of African descent. The disease is the major cause of blindness, presenting early and with advanced visual loss. An epidemiologic study is proposed with the major goals of a) measuring the prevalence of glaucoma and its associated impairment, b) evaluating its risk factors, and c) obtaining data to develop interventions to prevent or control visual loss. The proposed research would be the first comprehensive glaucoma study to cover an entire country. Because the disease is a major problem in Black populations, the aims of the proposed study are of widespread public health significance. The secondary goals of the study are to measure prevalence and evaluate risk factors for age-related cataract, macular degeneration, and diabetic retinopathy. Population based epidemiologic data on these diseases are limited or non-existent for Black populations; the proposed study would provide such information at limited additional cost. The above goals would be attained by examining a random sample of 4000 persons 40-84 years in a Ministry of Health polyclinic. Participants would have measurements of intraocular pressure, visual fields, visual acuity, refraction, height, weight, and blood pressure, as well as fundus photographs and an interview on medical, family, and other risk factor history. Blood testing would be performed on cases and a sample of noncases. To assess the feasibility of this project and test the proposed methods of recruitment and data collection, a pilot study was undertaken. Population participation in the pilot study, which examined about 200 randomly selected persons, was 95%. In Black persons >54 years, the prevalence of glaucoma with optic nerve damage was 13%. These results confirm the severity of the glaucoma problem and the need for the proposed study. Because its results would be applicable to other Black populations, the study has the potential to make an important contribution toward blindness prevention in other parts of the world. To further enhance the value of the data obtained, the study plans include a re- examination of the cohort to obtain five-year incidence and natural history data.